After Effects expressions cheat sheet: 12 lines you will reuse forever

Expressions in After Effects are not maths homework; they are shortcuts that replace keyframes you would otherwise set by hand a hundred times. This cheat sheet collects the twelve expressions we type most often, and the reason each one exists.

Start with looping. `loopOut("cycle")` repeats an animation forever from the last two keyframes, which is how most background loops, ticker bars and idle icon motion get built. Swap in `loopOut("pingpong")` when the motion should breathe rather than restart.

Next, controlled randomness. `wiggle(2, 12)` gives two shakes a second at twelve pixels of travel — enough to sell handheld camera drift without making the frame unreadable. Lower the frequency for a heavy camera, raise the amplitude for a nervous one.

Linking beats duplicating. Pick-whipping a scale property to a single slider control means one adjustment updates an entire lower third. Combine that with `thisComp.layer("CTRL").effect("Slider Control")("Slider")` and your comp becomes a rig other artists can drive without opening every layer.

For overshoot, an inertial bounce expression reads the velocity at the last keyframe and lets the property spring past its target before settling. It is the difference between motion that stops and motion that arrives.

Time-based tricks close the list: `time * 30` for constant rotation, `posterizeTime(12)` for stepped animation, and `valueAtTime(time - 0.1)` for follow-through on trailing layers.

In Ghostae Command you can describe the motion in a sentence instead of remembering syntax — the panel reads the selected layer and property, writes the expression, and applies it. But knowing these twelve patterns still makes you faster, because you can judge whether the generated expression is actually the right one.